WASHINGTON — Even if Howard Dean's own electoral ambitions are not realized, he may take credit for ushering in an era of movement politics that could have implications for the Democrats, and Republicans, for years to come.

More than any Democratic politician in years, Dean, the former governor of Vermont, has tapped into an intensifying bitterness among his party faithful toward the administration in power, and, through the Internet, has drawn a corps of citizens who had not paid heed to electoral politics. For Democrats, the payoff is that many of these new faces have views that fit the left wing of politics, the party's old-time base.

At the core of the movement is an anger stirred by the war in Iraq and, more broadly, by the rightward tilt of many policies in the Bush administration. President Bush has become the personification of much of this anger, but the Dean movement also seems to be reviving some long-held Democratic Party sentiments about the role of government in the life of the nation.

Through his assertive approach, or his clever tapping into the Internet, Dean has somehow put himself at the head of this parade. Democratic activists are now turning to him to answer — and remedy — all their concerns about the environment, social programs and the economy.

But the more Dean is viewed as the mouthpiece for the left, the more perilous his quest could be. The party's pragmatists are fearful. The danger, they say, is that Dean's success means that the Democrats could abandon the delicate machinations of Bill Clinton that pushed the party to the middle — and helped them take the White House. It was the first time a Democrat had won two terms since Roosevelt.

This invites another question: Could Democrats who accuse impassioned Republicans of refusing to compromise on their core principles now do the same? So much for any easing of gridlock.

Recognizing the Dean campaign's success, Republicans are already trying to compete by beefing up their own grass-roots operations and use of the Internet.

But at least some of Dean's success is because he presents himself as the candidate who best embodies the "anti-Bush." By seizing on his opposition to the war, Dean is essentially repudiating Bush.

Yet Dean is different from movement politicians of the past like Barry M. Goldwater and Ronald Reagan because they were far more ideological — and promoted an array of values and positions. By contrast, Dean resembles George McGovern and Eugene McCarthy, Democrats whose appeal was founded in their antiwar positions but could not sustain their support because they had little to say when the war ended.